How Would I Go About Making A Plastic Product/Mold For Something?

I've always wondered this because I have 3 really good ideas, and have always wanted to get them made into legitimate plastic products.

One of the products I already made with pieces from home depot, and its basically an aquarium vacuum on steroids. It works in a very cool/innovative way (nothing like you've seen in petsmart before), that I think I could sell to many fish enthusiasts. I've owned fish tanks all my life, and it was developed to avoid many of the common problems that most vaccums suffer from.

But it was made mainly for "engineering" reasons to see if it works, which it does (it actually blew my mind that it worked so well). So my goal is to have it converted into a cleaner looking plastic model. If there was a way to have pieces molded, I could make it a lot smaller and more compact/efficient.

My second and third ideas, would help a lot more people, in a much simpler way, so I'd rather not talk about them tbo.

But my question is I want to learn how to work with plastic. How to make molds, and have custom made parts made up. Does anyone know how to get this done?

Thanks WF! - Red